Shearhead for dry shaving apparatus



March 27, 1956 P. KOBLER 2,739,380

SHEARHEAD FOR DRY SHAVING APPARATUS Filed July 9. 1952 law 79 27 FIG.12

79 28 INVENTOR.

20 By 0 W SHEAPHEAD FOR DRY SHAVING APPARATUS Paul Kobler, Lynbrook, N.Y., assignor to Victor Kobler and Werner Kobler, both of Zurich,Switzerland Application July 9, 1952, Serial No. 297,945

Claims. (CI. 30-43) The present invention relates to a shearhead for dryshaving apparatus which shearhead comprises a hollow outer member and aninner cutter member located with said outer member and movable relativethereto, said outer member having openings extending therethrough forpassage of hairs to the inner cutter member to be cut thereby, the outercutter member being so formed that part of its outer surface is higherthan other parts and thus presses more strongly against the skin beingshaved, at least some of said openings in said higher part beingbordered by sharp edges. The shearhead preferably has a transverselyslotted hollow outer cutting member and a transversely slotted innercutting member reciprocable within and longitudinally of said outercutting member for cooperation therewith. More particularly, thisinvention relates to a shearhead of the said kind in which the saidouter cutting member, which may be straight or curved in longitudinalprofile, has two inner surfaces defined, in transverse section, by apair of straight lines intersecting each other at an obtuse angle andtwo outer surfaces defined, in transverse section, by straight linesparallel to those defining the said inner surfaces.

As well known in the art, it is desirable in such shearheads that thethickness of the outer cutting member, that is, the distance between thesaid parallel outer and inner surfaces thereof be as small as consistentwith an adequate strength of the cutting member, in order to ensure thata close shave can be obtained. In the region of the oblique intersectionof the two inner and the two outer surfaces, however, the outer cuttingmember of such shearheads has a thickness which is greater than that between the parallel inner and outer surfaces, and greater than requiredfor warranting sufiicient strength, so that the closeness of the shaveis unnecessarily impaired in the said region of the outer cutting memberwhere the said member is highest and presses most strongly against theskin being shaved.

It is one of the objects of the present invention to avoid this drawbackand to provide a shearhead in which the thickness of the outer cuttingmember in the said region is made as small as desirable.

Other objects and advantages of the invention will become apparent fromthe description now to follow of a preferred embodiment thereof, inwhich reference will be had to the accompanying drawing, in which:

Fig. 1 is a longitudinal section of a shearhead according to theinvention;

Fig. 2 is a partial plan view of the shearhead of Fig. 1 at an enlargedscale,

Fig. 3 shows in perspective part of the shearhead, with portions thereofcut away to show its transverse section;

Figs. 4 and 5 show at an enlarged scale partial crosssections alonglines IVIV and VV, respectively, of Fig. 2.

Figs. 6, 7 and 8 are partial longitudinal sections, taken on lines VIVI,VII-VII and VIII-VIII, respectively of Figs. .4 and 5 and showing at anenlarged scale certain details of the outer cutting member;

Patented Mar. 27, 1956 v if on the housing 3 of the-apparatus. This basepiece carries an outer cuttingmember 4 which is in the general form of alongitudinally arched inverted U-shaped channel and the parallel flangesof which are riveted at 5 to the base piece 1. In its top portion, theouter cutting member is provided with a series of equidistant transverseslots 6 leaving between them small bridges 7.

The base piece 1 has a longitudinal groove 8 guiding an inner cuttingmember 9 in the shape of a ring segment having an enlarged rim intowhich are cut equidistant transverse slots 11 leaving between them aseries of teeth 12. The top face of these teeth 12 conforms to the innerface of the bridges 7 left between the slots 6 and is wider, in thelongitudinal direction of member 9, than the said slots so that theteeth 12 cannot engage the slots 6 and the inner cutting member 9 ismaintained in its guiding groove 8 by the outer cutting member butcapable of longitudinal motion along the latters inner face. Moreover,the inner cutting member has a recess 13 engaged by an actuating lever14 extending through a wide opening 15 in the base piece 1. Thisactuating lever is pivoted on a pin (not shown) in the housing 3 and inoperation is oscillated by an electric motor and suitable transmissionmeans (not shown) lodged in the said housing. Thus, the inner cuttingmember 9 will be reciprocated along the inner face of the outer cuttingmember 4 and any hair which extends into the slots 11 through the slots6 when these slots register will be shorn off between the adjacentbridge 7 and tooth 12 as the inner cutting member 9 moves with respectto the outer cutting member 4.

Referring now particularly to Figs. 4 and 5 which show transversesections of the top portion of the outer cutting member 4, taken atvarious points thereof, the said outer cutting member 4 has two innersurfaces 17 defined and represented by a pair of straight linesintersecting each other sit-18, at an obtuse angle. Further, the outercutting member has two outer surfaces 19 also represented or defined bya pair of straight lines which are parallel to those representing theinner surfaces 17. In Fig. 5, which is a cross-section taken though anend portion of member 4, the lines indicating the surfaces 19 intersecteach other at 20, which indicates an obtuse edge along which thesurfaces 19 meet each other.

In the central portion of member 4, however, the surfaces 19 do not meetbut there is between them a third surface which may have variousshapesas seen in transverse section. As shown in Fig. 4, this third outersurface 21a is defined by an arc of circle the center of which is at 18,where the inner surfaces 17 of the member meet each other. Accordingly,the thickness of the outer cutting member is the same everywhere,whether measured between the surfaces 17 and 19 or between the edge 18and the surface 21a. Fig. 9 represents an alternative shape of saidsurface which, in this case, is represented in transverse section by astraight line 21b. Preferably, the distance between the surface-21a andthe said point 18, and accordingly the thickness of the outer cuttingmember in this region, is at most equal to that between the inner andouter surfaces 17 and 19, respectively. It will be understood that allthe surfaces 17, 19 and 21a as well as their edges 18 and, Wherepresent, 20, are interrupted from place to place by the slots 6 and infact appear only on the bridges 7; nevertheless, they'will be referredto for the convenience of the description, as if they were continuous.

Figs. 6 to 8 are enlarged cross-sectional views taken longitudinally ofthe shearhead through various portions of the outer cutting member toshow the cross section of the bridges 7. :Fig. .6 representsa normalcross-section through three bridges 7 and applies both tothelongitudinal portion of the outer cutting member the transversesectionof which isshown in Fig. 4, and the longitudinal portions shownin transversesection in-Fig. 5. It will be seen from Fig. 6 that thoseouter edges 2.? of the bridges 7 where the slots 6 meet theportionsof'the outer surfaces designated 19 are rounded, while the edges 23 ofsaid bridges where slots 6 meetthe inner surfaces 17 are sharp; thesesharp edges-23 being, :in fact, :the cutting edges of the outer cuttingmember.

Fig. 7 is an enlarged longitudinal cross-sectional view of the outercutting member, showing three bridges 7 in cross-section and applyingonly to the end portions, having the transverse section shown in Fig; 5.Fig. 7 differs from Fig. 6 in that its plane-passes through the edges 18and 29 (Fig. that is, obliquely with respect to the surfaces 17 and 19.Therefore, theheight of the bridges 7 is. greater in Fig. 7 than in Fig.6, but otherwise the two figures are identical especially in that theouter edges. of the bridges are rounded at 22 and the inner edgesthereof are sharp as at 23.

Fig. 8 is a longitudinal sectionsimilar to that of Fig. 7 but taken inthe central portion of member 4 to which Fig. 4 applies. The height ofthe bridges 7 in this section, which is the distance between the surface210 and the edge 18, therefore is smaller than in Fig. 7. In theparticular embodiment shown, in which the surface 21a is defined by anarc of circle the center of which is on edge 18, the height of thebridges 7 in the section according to i Fig. 8 is equal to that in thesection according to Fig. 6. In alternative embodiments, however, suchas that shown in transverse section in Fig. 9, the said height of thebridges, that is, the distance between point 18 and the center ofsurface 21b is smaller in the section according to Fig. 8 than in thataccording to Fig. 6.

As shown in Fig. 8, the edges 24 of the bridges 7 at which the slots 6meet the outer surface 21a are sharp. This will conveniently be achievedby first grinding the surfaces 19 and the slots 6 with their commonrounded edges 23, throughout the length of the cutting member 4, to theshape indicated in Figs. 5, 6 and 7 required for the end portions of themember and indicated in dash-and-dot lines in Fig. 8. Thereupon, thesurface 21:: is ground in a second operation whereby the material inexcess including the rounded edges 22 is removed so as to provide thesharp edges 24. Longitudinally of the outer cutting member ,4, the saidsurface may be carried out in various shapes. As particularly shown inFigs. 1 and 2, the surface is ground to the same depth over a centralportion of the length of member 4, including a certain number. ofbridges 7 for which the transverse profile of the cutting membercorresponds to either Fig. 4 or Fig. 9. In an alternative embodimentshown in plan View in Fig. 10, the surface 210 has a longitudinalcurvature which is less pronounced than that of surfaces 19, or it evenmay be straight in longitudinal profile. Thus, the depth to which andthe width on which surface 21c is ground from the surfaces 19 increasesfrom both endstowards the middle of said surface 21c. Each of thebridges accordingly-differs in shape from the adjacent ones, so that thetransverse section shown in Fig. 4, or that shown in Fig. 9, applies toonly one or twoindividual bridges 7, with theremaining bridges differingin shape therefromby having either a wider surface and accordinglysmaller height at their apex, or anarrower surface 210 with greaterheight at their apex than the said one or two bridges.

In still another embodimenhshown in plan view in is- ,l .th.. i r .s 2..4 extend th sus c th len th o h llttinsmembs 14.. n wh ch cas t t asvers ct on .4 may be as shown in Fig. 4 or in Fig. 9 while at no partis it asshownin Fig. 5.

The described shearhead having an outer surface as shown at 21a, 21b,210, or 21a, has the following advantage: In the shaving process, theouter surfaces 19, 21a, 21b, 21c, or 21d of the shearhead are pressedagainst, or maintained in contact with, the skin of the person to beshaved and the hair extending through the slots 6 will be cut offbetween the inner cutting member 9 and the outer cutting member 4 at thelevel of the inner surface 17 of the latter when the inner cuttingmember is reciprocated. Thus, to obtain a close shave,- it is desirablethat the distance between the outer and the inner surface of the outercutting member, that is the height of the bridges 7, be as small in thecuttingregion as is consistent with a sufficient strength of theseelements. Where the transverse section of the outer cutting member is asshown in Fig. 5, it will be noted that in the region of the point 20 theheight of the bridges '7 is greater and accordingly the shave less closethan in other regions, although such increased height of the bridges 7is not necessary togive the bridge its required strength. Now, due-tothe obtuse angle at-which the two-surfaces 19 are situated, theedge 29in such transverse section as shown in Fig. 5 is the point at which thesurface-is highest and pressed most strongly against the skin. and theskin is besttensioned and applied to theishearhead so that the optimumshave will occur at this point. If therefore the shave is not closeenough at this point, it will be difiicult for the user to obtain aclose shave at all. This drawback is overcome according to'the inventionby providing on atleast'pait of the length of the shearhead thedescribed outer surface 21a, 21b, 210, or 21d which is at a smallerdistance from the inner surfaces 17 or their intersection 18 than theedge 20 would be. The provision of this surface 21a, 21b, 210, or 21dthus materially improves the closeness of the shave. In the embodimentrepresented in Fig. 4 the distance between said,

surface-21 and the edge. 18 is the same as the thickness of the-materialbetween the innerand outer surfaces 17 and 19 respectively, so thatthe-provision'of surface 21a, 21b, 21c, or,21d will not affect thestrength of the bridges 7. In fact, it-may even beadmissible to have atthis point a smaller thickness. of material than in the adjacentregions, so that the surface may still be set a little deeper.

Regarding Figs. 6 to 8, it will be noted that the provision of roundededges 22 in the region of the outer surfaces 19 favours thebulging ofthe skin into the-slots 6 whereby the shave will be substantially closerthan if the skin where tensioned flat over the surfaces 19. If, however,this desirable bulgingv of the skin were also favoured by rounded'edgesin the region of the surface 21a, 21b, 21c, or 21d inwhich the height ofthe bridges 7 is reduced and the tension of theskin over the apex of theshearhead is increased, the skinrnight bulge at this point beyond theinner surface 17 of the outer cutting member, become engaged with theteeth 12 of the inner cutting member 9 andbe damaged or irritated bythem. This is avoided by the provision of the sharp edges 24' of theouter surface 21a, 21b, 210 or 21d, a featurewhich tends to reduce thebulgingof the skin into the slots 6.

Althoughthe-intermediateouter surface may beextended to the full lengthof shearhead as shown in Fig.'11, without departing from "the scope ofthe invention, the provision. of :end portions not provided with suchintermediate surfaces as shown in Figs. 2 and 10 has the advantage thatit ensuressome additional tensioning of the skin in a longitudinaldirection between'such-end 'portions andaccordinglvabetter shave inthe-region of the surfaces of the intermediate portion ofthe shear-headin which they:- are provided.

Asshown inFig. 12, the shavingapparatus may comprise three shearheads26, 27 and 28, the two outer shearheads 26 andZB having no intermediatesurfaces and the iniddleshearheadfl having such surfacesinitslongitensioned in transverse direction between the shearheads 26 and Z3,and in longitudinal direction between the end portions of the shearhead27 so as to receive its optimum shaving in the central portion of thelatter.

While the shearhead shown in the drawing is longitudinally curved, itwill be understood that its longitudinal profile could be straightWithout departing from the scope of the invention.

What I claim is:

1. In a mechanical shaver shearhead, an outer cutter, an inner cutteradapted to be moved relative to said outer cutter in operation, saidouter cutter having an outer surface for engaging the skin to be shaved,said cutter surface being formed with a portion thereof at a higherlevel than other portions so that said higher portion presses againstthe skin more strongly than said lower portions, said outer cutterhaving openings extending therethrough to said inner cutter forpermitting hairs to pass inwardly to said inner cutter to be cut, theedges of said outer cutter bordering some of said openings being sharpat said portion of said outer cutter which is higher and presses morestrongly against the skin, and said edges being rounded at the portionswhich are lower and press less strongly against the skin.

2. A shearhead according to claim 1 and in which the outer cutter, atthe higher portion thereof where the edges of said opening are sharp, isof less thickness than the lower portions where the edges bordering saidopenings are rounded.

3. A shaver according to claim 1 and in which the openings bordered bysharp edges are arranged in an elon ated portion of the outer cuttermember extending along a line disposed longitudinally and centrally ofsaid outer cutter member, said elongated portion being bordered on allsides by said portions of said cutter member which are provided withsaid openings bordered by round edges.

4. A shearhead according to claim 1 and in which a portion of theopenings bordered by said sharp edges of the outer cutter member arepositioned at an area of said outer cutter member which is surrounded onall sides by an area of said outer cutting member which is provided withopenings bordered by rounded edges, the thickness of the outer cuttermember at the area provided with the openings bordered by sharp edgesbeing less than the thickness at said surrounding area.

5. In a mechanical shaver shearhead, an outer cutter, an inner cutteradapted to be moved relative to said outer cutter in operation, saidouter cutter having an outer surface for engaging the skin to be shaved,said outer surface being formed with a portion thereof at a higher levelthan other positions so that said higher portion presses against theskin more strongly than said lower portions, said outer cutter havingtransverse slots extending therethrough to said inner cutter forpermitting hairs to pass inwardly to said inner cutter to be cut, theedges of said outer cutter bordering said slots being sharp at saidportion of said outer cutter which is higher and presses more stronglyagainst the skin, and said edges being rounded at the portions which arelower and press less strongly against the skin.

References Cited in the file of this patent UNITED STATES PATENTS2,036,557 Viall et a1 Apr. 7, 1936 2,079,294 Lewis et al. May 4, 19372,559,772 Kobler et al July 10, 1951 2,562,104 Kobler et al July 24,1951 FOREIGN PATENTS 147,119 Austria Oct. 10, 1936

